Hillary Clinton has hit out Donald Trump over his recent immigration policies.

Speaking to Ryan Tubridy on RTÉ Radio 1, in an interview recorded last week, Ms Clinton said her country had started "a very cruel attack on little children who are taken away from their parents who cross our border."

Ms Clinton said she was opposed to opening up the border but that separating families was not right.

"Crossing our border is a misdemeanour and I am not one who says you just turn a blind eye and open the border.

"But I am adamantly opposed - I am anguished over taking infants and toddlers and little children away from their parents and sending them who knows where across the country.

"And you stop to think 'this is not necessary. Why is this being done?'

It's being done to stoke those flames of anger and resentment and hate that are unfortunately rearing their ugly heads in our politics.

President Donald Trump created a storm of controversy over his immigration policy causing family separations at the US southern border.

Nearly 2,000 children were separated from their families over a six-week period in April and May after Attorney General Jeff Sessions announced the new “zero-tolerance” policy that refers all cases of illegal entry for criminal prosecution.

Last week, Mr Trump signed an executive order ending the process of separating children from families after they are detained crossing the US border illegally.

It was a dramatic turnaround for Mr Trump, who has been insisting, wrongly, that his administration had no choice but to separate families apprehended at the border because of federal law and a court decision.

When asked by Tubridy if Mr Turmp would have felt he went too far, Ms Clinton said she felt the U-turn was merely down to optics.

"I think what he concluded was that the optics looked bad for him.

"And Republicans, who are going to face the voters in November, were telling him 'you got to fix this because people are organising against it in my constituency and this could backfire'."

"But if you listen to what he [Mr Trump] said, he said that they would go back, but here's what I am incredibly focused on and worried about - they've already separated 2,000 children.

Now some of the children are in places that are easy to go recover them but I don't believe they have a very good system for matching children and parents, they have just scattered them all to the four winds.

"And there are a number of very young children who have been sent all over the United States to be put into foster homes.

"These children can't speak for themselves. I was reading the online news this morning and three-month-old babies, eight-month-old babies, two-year-old babies - they can't speak for themselves.

"They can't really say where they last saw their parent and where that parent was picked up and where that parent may now being detained or may be having been deported.

So I worry that a significant number of these children will not be reunited with their parents and that would be an immoral stain on our country that we did this and broke up these families. It's a separate issue from enforcing laws.

The wide-ranging interview also touched on the US president's meeting North Korean leader Kim Jong Un.

Ms Clinton said "the jury is out" on whether it was a success and said she would applaud Mr Trump if it proves so, but added that she would say "shame on you" if it was just a photo opportunity.

The former Secretary of State also said Ireland was experiencing great youthfulness with the election of our current Taoiseach and seeing the result of the recent referendum.

"It's young people, not only in the highest elected position and the youngest taoiseach in your history, as I am told - it's young people saying we want a role and a voice in our future."